Double limit switch



Nov. 14, 1933. M. E. HENNING 1,935,029

DOUBLE LIMIT SWITCH Filed OCT.. l5,A 1929 MN @www a2,

66 registers with the pin 64, the switch structure is in on position.When either of the cam surfacesy 66h or 66o coact with the pin 64,however, as shown by` dotted lines and when the float shaft 44 is rockedin opposite directions as shown by trical devices for controlling thesame depending upon the level of the liquid in the container 5f). Thecontainer 50 in the illustration of Figure 1 is a gravity tank theliquid 62 of which is oil to be supplied to a burner. The liquid 62 issupplied to the container 5D from a storage tank 70. A supply pipe '72leads from a check valve in the bottom of the tank 'l0 to a pumpstructure '14 connected with the pump motor GB. The discharge of thepump 74 is indicated at 76 and is located within the container .5owhereby oil pumped from the storage tank 70 enters the container' 50.

Practical operation In the operation of my device in the installationillustrated, the switch is shownl in on position so that the pump "1liwill be operated by the motor G8 :'or pumping liquid into the container50. The level oi the liquid will accordingly rise and carry the iioat 56upwardly with it until the oat engages the collar 5d after which the rod54 will be raised to the dotted line upper position shown. in Figure `4.This causes the cam member 66 to assume a corresponding position asshown in dotted lines in Figure E so that the cam surface 66h thereofwill move the switch arm 20 to oil position as shown in dotted lines.The motor 68 will immediately stop and as the liquid in the container 50is used, the level thereof will lower until the parts assume the fullline posi tion shown in Figure 2. The motor and pump will immediatelybegin to operate ior again iilling the container lill.

However, if there is no oil in thetanlt 'lo to be pumped into thecontainer 5o, use of the oil from the container 5@ will keep on loweringthe level thereof while the pump is operating without drawing any oilinto the container 50. When the level o f the liquid 62 consequentlyreaches a low position as shown by the lower dotted level in Figure 4,the 'float 56 will engage the collar 60 and the weight of the iioat willmove the rod 54 downwardly and the arm 52 to its lower dotted position.This causes the cam 66 to be rotated so that the cam surface 66o engagesthe pin 64 for moving the switch arm to oir position so lthat the pumpdoes not continue to operate indefinitely without any supply oi oilbeing provided for it.

When the tant: 'lil is again refilled a push button 78 on the switchstructure is pushed downwardly to the dotted line position shown inFigure 3 for moving the switch arm 20 to on position. The switch is heldin this position until the level oi the liquid 6H is suiilciently highto cause the float titi to float. rlihe push button 78 may then bereleased and will move upwardly due to a spring il@ thereunder.

The push button 'lll is connected by a rod with an insulating button 84which engages the bumper spring 38 of the switch arm 20. A sleeve 86 isprovided on the lid 12 ofthe switch casing through which the rod 82 isslidably mounted.

Although I have illustrated my double limit switch in connection with afloat device so that the switch will be turned off when the level of aliquid lowers to an abnormal position, the cam arm 52 may be connectedwith any other type of motive device desired, such as a diaphragm so asto control electric devices according to pressure or temperature insteadoi liquid level. The illustration in Figure l is merely to show how thedevice may beapplied to a storage tank and a gravity tank for an oilburner.

Some changes may be made in the construction and arrangement of theparts of my device without departing from the real spirit and purpose oimy invention, and it is my intention to cover by my claims, any modifiedforms of strucn ture or use of mechanical equivalents, which may bereasonably included within their scope.

I claim as my invention:

l. In an automatic control switch, a movable two position switch member,magnetic means for normally constraining said switch member to one ofits positions, a rock shaft, a member thereon of resilient material bentto form a depression and a riser portion on each side of saiddepression, condition responsive means for automatically rocking saidrock shaft, an abutment on said switch arm, said depression and saidriser portions being adapted to register' therewith for resilientlyoperating said switch member to allow it to remain in said mentionedposition when the depression registers therewith and to cause it to moveto the other of its positions when either of said riser portionsregister therewith.

2. In a double limit control switch, a movable two position switchmember, magnetic means for normally constraining said switch member toone oi. its positions, a rock shaft, a resilient cani lever thereon bentto form a depression and a riser portion on each side of saiddepression, a single abutment on said switch member, said depression andsaid riser portions each being adapted to register therewith foroperating said switch member to allow it to remain in said mentionedposition when the depression registers two position switch member,magnetic means jV for normally constraining said switch member to one oiits positions, a resilient rockable member having a depression and ariser portion on each side ci said depression, an abutment on said illeill]

switch arm,v said depression and said riser pori 'tions being adapted toregister therewith for operating said switch member to allow it toremain in said mentioned position when the depression registerstherewith and to cause it to move under the resilient tension of saidrockable member to the other of its positions when either of said riserportions register therewith.

MALCOLM E. HENillli i5?.

